Laoptop problem with projector

I have a Dell inspiron E1405/windows XP Pro.
A few month back I installed Samsung SynchMaster 205BW 20″ monitor. The laptop works fine with the external monitor and without it.
The trouble is when connected to a projector instead of the external monitor, the display gets out of control. The fonts get very large (in powerpoint) in the area where I click the mouse. Also, the mouse wheel shrinks fonts in a browser to a tiny size. There is also a rapid ticking noise as if something is pressing on the keyboard very fast.
Any help will be appreciated.